For low-volume electronic devices capable of supplying a large amount of power, power converters must be of very high efficiency since losses in the power converter must be dissipated from the low volume and surface of the power converter, which is required to exhibit a high performance to accommodate large changes in load current between idle and active power states with acceptable transient response. Currently, on-board distributed power system applications include development of power converters capable of providing high power densities using topologies for high frequency ranges and efficiencies of about 90%.
Because of alternating current is preferred for efficient power transmission, power sources generally provide power at alternating current, but the operation of the electronic devices demands direct current (DC), which is provided by converting the current supplied from alternating to direct using rectifiers. For this, a wireless power receiver includes a rectifying circuit for converting received radio frequency (RF) signals in the form of AC waveforms to DC waveforms that are adjusted to have a determined voltage level at the output terminals.
Half-bridge rectifiers are commonly used in power converters to provide half-wave rectification of alternating current. A typical half-bridge rectifier include two diodes which are inherently inefficient conductors producing a number of well-known problems. One problem resulting from the inefficiency of diodes is that they produce a forward voltage drop. This is most noticeable in low-voltage power converters where the voltage drop may be a significant proportion of the desired voltage output. Apart from reducing overall efficiency of the power converter, resulting high temperatures also reduce the reliability of components. Thus, additional design effort may be required to overcome the problems, and other factors such as the dimensions of the system, which may be affected as a result.
As most electronic devices require smooth DC current to operate properly, adding a capacitor to the output of a half-wave rectifier filters pulsating DC into smooth DC, but filter capacitors are a major concern in determining cost, size and weight in design of a rectifying circuit. Moreover, difficulties arise in the implementation of the rectifying circuit due to constraints from the available mounting area and requirements for high output and efficiency, since the rectifying circuit typically uses passive devices having large external parameters. Additionally, the rectifying circuit does not operate over a large range of frequencies since it is an external packaged active device. Therefore, it is possible to manufacture a rectifying circuit that may be smaller and lighter than a conventional rectifying circuit, including a reduced number of passive devices, such that a stable DC output power may be obtained at the output terminals of the wireless power receiver in which the rectifying circuit is to operate. Benefits of half-wave rectification may reduce increased expenses and circuit complexity to achieve high power densities and power transmission efficiency.
Based on the foregoing, there is a need for a rectifier, which may be integrated with a boost converter and designed based on an architecture and circuit topology capable of providing high power densities.